In most presently manufactured vehicles, such as automobiles, bumper apparatus is provided at at least one end of a vehicle, and generally at both ends, so that at least one bumper extends transversely of the vehicle at a predetermined distance from the surface on which the vehicle is supported. Additionally, the vehicle frame and body are generally coupled resiliently to the vehicle wheels, or other supporting members, in order to increase the riding comfort of vehicle passengers. Since the bumper is attached to a portion of the vehicle body or frame, the bumper moves with the body or frame relative to the traveled surface. In an automobile, relative movement between the automobile body and a roadway may result, for example, from variations in the load carried by the automobile or from unevenness of the roadway. Considerable reduction of the vertical distance between an automobile body and the roadway may also occur upon sudden braking of the automobile.
Variations in the distance between an automobile bumper and a roadway diminish the effectiveness of the bumper in the event of a collision because the bumper may not be located at its most effective height. In particular, the bumper will be more effective if it coincides with the bumper of another automobile, for example, involved in the collision. Even if one automobile is struck on its side, however, it is preferable for the bumper of the striking automobile to be located at a generally constant distance from the roadway at all times so that lateral reinforcement in the sides of automobiles can be located in relatively limited regions of the automobiles sides.
One approach to overcoming the disadvantages inherent in mounting a bumper on a resiliently supported automobile frame or body is to design the bumper with a vertical dimension sufficiently great to compensate for all vertical movements of the bumper relative to the roadway. Such a bumper would resemble a platform, however, and would present a relatively unattractive appearance. In some automobiles, a vertically extended bumper would also adversely affect the operation of other mechanisms in the automobile, such as the cooling system for an engine located in the front of the automobile.